1. Field of the Invention
This invention relates to a hermetically sealed type dynamic pressure fluid bearing motor in which a rotatable member such as a rotatable polygonal mirror is supported by a dynamic pressure fluid bearing provided in a hermetically sealed case, as seen in a polarization scanning motor or the like.
2. Related Background Art
In a polarization scanning motor for rotatably driving a rotatable polygonal mirror in a laser beam printer or the like, it is required that irregularity of rotation be made small even when there is a large temperature change also, high accuracy is required of a rotatable member bearing portion therefor.
On the other hand, as means for securing high bearing accuracy, use is made, for example, of a dynamic pressure fluid bearing which supports a rotatable member with the dynamic pressure of fluid generated by the rotatable member.
The prior-art materials for a motor using a dynamic pressure fluid bearing are as follows.
1) Japanese Laid-Open patent application No. 58-5518 discloses a dynamic pressure type spindle device using a dynamic pressure type cylindrical channel bearing.
2) U.S. Pat. No. 4,487,514 shows a motor having a dynamic pressure type bearing using error lubrication.
3) U.S. Pat. No. 4,652,149 shows a dynamic pressure fluid bearing according to the applicant's prior application.